The West African Ebola outbreak is the worst in history, with the World Health Organisation (WHO) already declaring it an international health emergency.

Ebola is one of the world's most deadly diseases, with no known vaccine or cure. The Zaire strain - the one currently spreading through West Africa - can kill up to 90 per cent of sufferers, although in the latest outbreak the death toll has been around 55 per cent. To date, it has killed nearly a 1000 people with about 1800 infected.

Last week, two of the worst-hit Ebola countries - Liberia and Sierra Leone - brought in troops to enforce quarantines and stop people infected with the disease from traveling.

Liberian President Ellen Johnson Sirleaf said no one with a fever would be allowed in or out of the country and warned some civil liberties could be suspended if needed to bring the virus under control.

Screening measures have been introduced in New Zealand airports in a bid to stop the deadly Ebola virus reaching here. Anyone who in the past three weeks has visited West African countries affected by the Ebola outbreak would be screened for symptoms of the disease.

People arriving from those areas would also be given information about the symptoms of Ebola and how to seek help in New Zealand if they became unwell.